Factors Affecting Temperature Distribution
Geography › Atmosphere and Temperature · Topic 6.4
The temperature at a place depends mainly on latitude, which decides the angle of the Sun's rays and the length of day, and on altitude, distance from the sea, ocean currents, prevailing winds, cloud cover, the nature of the surface and the slope of the land. Together they explain why places on the same latitude can have very different temperatures, and why a high mountain near the equator can be cold.
6 min read · UPSC Prelims · Geography · Atmosphere and Temperature
At a Glance
- Latitude Angle of rays and day length
- Altitude Falls about 6.5 degrees per km
- Distance from sea Maritime versus continental climate
- Ocean currents Warm and cold currents change coasts
- Local factors Winds, cloud, surface, slope
- Exam link UPSC Prelims, Geography: Atmosphere and Temperature
Where Does It Fit?
This is the fourth topic of the category on the atmosphere and temperature. The previous topic explained how the Earth is heated and how the heat budget balances, and this one lists what makes temperature differ from place to place. The next topic covers the horizontal distribution of temperature. Previous topic: Heat Transfer and Heat Budget of the Earth. Next topic: Horizontal Distribution of Temperature and Latitudinal Heat Balance.
Why Does Temperature Vary from Place to Place?
In short: latitude sets the basic heat, and altitude, sea, currents, winds and surface adjust it.
The air is heated mainly from below, by contact with the warmed surface, and so the temperature of a place depends on the amount of insolation received and on how the surface and atmosphere handle it, as in Heat Transfer and Heat Budget of the Earth. The main factors affecting temperature are described below. The air temperature is measured at a standard height of about 1.2 to 2 m above ground, in the shade, and the daily mean is the average of the highest and lowest values. The daily range is the difference between the day’s maximum and minimum, and the annual range is the difference between the warmest and coolest months.
How Does Latitude Matter?
Latitude is the most important factor. The amount of insolation received depends on the angle of the Sun’s rays and the length of the day. Near the equator the Sun’s rays fall nearly vertically and cover a small area, giving high temperatures, while near the poles they are slanting, spread over a larger area, and pass through more atmosphere, so less heat is received per unit area. Hence temperature generally decreases from the equator to the poles, as shown by the heat zones in Latitudes and Important Parallels. Seasonal variation also increases with latitude, as in Solstices, Equinoxes and Variation in Day Length.
How Do Altitude, Sea and Ocean Currents Matter?
- Altitude: the atmosphere is heated mainly from the ground, so temperature falls with height at the normal lapse rate of about 6.5 degrees Celsius per km. Thus hill stations such as Shimla, Ooty and Darjeeling are cooler than the plains nearby, and Quito, on the equator at about 2,850 m, has a cool spring-like climate. Snow lies on Kilimanjaro, near the equator.
- Distance from the sea (continentality): water heats and cools slowly because of its high specific heat, and land heats and cools quickly. Places near the sea have a maritime climate with a small annual range, mild winters and cooler summers, as at Mumbai. Places far from the sea have a continental climate with extreme heat and cold, as at Delhi, Nagpur and Verkhoyansk in Siberia, which has an annual range of over 60 degrees.
- Ocean currents: warm currents raise coastal temperatures, and cold currents lower them. The warm North Atlantic Drift keeps the ports of western Europe, such as northern Norway, ice-free in winter, and the cold Labrador and Humboldt currents cool the coasts of Newfoundland and Peru. The effects are in Effects of Ocean Currents.
- Prevailing winds: winds from the sea bring moderate temperatures, and winds from the land bring extremes. The western coasts in the westerlies have a mild climate, and the interiors have a harsh one.
What Are the Other Factors?
| Factor | Effect |
|---|---|
| Cloud cover and humidity | Clouds reduce daytime heating by reflecting insolation and reduce night cooling by trapping heat, so cloudy places have a smaller daily range |
| Nature of the surface (albedo) | Snow and light sand reflect more; dark soils, forests and cities absorb more |
| Aspect of slope | In the northern hemisphere, south-facing slopes get more sun and are warmer than north-facing slopes; this is evident in the Himalaya, where settlements and orchards lie on sunny slopes |
| Relief and mountain barriers | Mountains block cold or warm winds; the Himalaya shield India from cold Central Asian winds |
| Vegetation and soil moisture | Forests moderate temperature through shade and transpiration; dry bare soil heats quickly |
| Urbanisation | Cities are warmer than surroundings, forming urban heat islands, because of concrete, asphalt and waste heat |
As an analytical point, the factors do not act alone but interact, so a good answer on any place combines them: the temperature of a hill station depends on its latitude and altitude, and also on its distance from the sea and its slope, and the Himalayas, for instance, alter regional temperature patterns in ways beyond altitude alone.
How Can These Factors Be Seen on a Map?
Lines joining places of equal temperature are called isotherms, and on a map they trend east-west over the oceans but bend over the continents because of the differences in heating of land and sea. The patterns they show are in Horizontal Distribution of Temperature and Latitudinal Heat Balance, and the temperature falls with height are covered in Vertical Distribution of Temperature and Temperature Inversion.
Why Is This Topic Important?
- Concepts Continentality and currents
- India Altitude and hill stations
- Application Explains regional climates
What Came Next?
The next topic describes the horizontal distribution of temperature and the latitudinal heat balance. Next topic: Horizontal Distribution of Temperature and Latitudinal Heat Balance.
Key People and Terms
- Continentality Inland effect on temperature
- Annual range Difference between warmest and coolest months
- Isotherm Line of equal temperature
- Lapse rate Fall of temperature with height
- Urban heat island City warmer than surroundings
- Aspect Direction a slope faces
Exam Corner
Points to Remember
- Latitude is the most important factor.
- Temperature falls 6.5 degrees per km.
- Land heats and cools faster than water.
- Warm currents raise coastal temperatures.
- Isotherms join places of equal temperature.
Do Not Confuse With
- Maritime and continental climate Small versus large range
- Warm and cold currents Raise versus lower coastal temperature
- Daily range and annual range One day versus one year
Memory Hook
Latitude leads, altitude lowers, sea softens, currents shift, slope and cloud adjust.
Mains Angle
Questions ask for factors with examples. These points add depth.
- Primary Latitude and altitude
- Sea Continentality and currents
- Local Slope, surface, cities
A Question You May Face
An original practice question, not a past paper question.
“Explain the factors that influence the distribution of temperature at the surface of the Earth.”
How to Answer
- Latitude Sun’s rays.
- Altitude Lapse rate.
- Sea and currents Moderation.
- Local Slope and surface.
GS Relevance
Frequently Asked Questions
What are the main factors affecting temperature distribution?
The main factors are latitude, altitude, distance from the sea, ocean currents and prevailing winds, along with cloud cover, the nature of the surface, the aspect of the slope, mountain barriers, vegetation and urbanisation. Latitude is considered the most important.
How does altitude affect temperature?
Temperature falls with height at the normal lapse rate of about 6.5 degrees Celsius per km, because the atmosphere is heated mostly from the ground and the air thins with height. This is why hill stations such as Shimla and Ooty are cooler than the plains.
What is continentality?
Continentality is the effect of distance from the sea on climate. Land heats and cools faster than water, so places far from the sea have hot summers and cold winters with a large annual range, while coastal places have moderate temperatures and a small range.
How do ocean currents affect temperature?
Warm ocean currents raise the temperature of the coasts that they pass, and cold currents lower it. The warm North Atlantic Drift keeps the ports of northwest Europe ice-free in winter, while the cold Humboldt Current cools the coast of Peru and Chile.
Why do south-facing slopes in the northern hemisphere get warmer?
South-facing slopes in the northern hemisphere receive the Sun's rays at a more direct angle and for longer than north-facing slopes, so they get more insolation and are warmer and drier. In the Himalaya, this is why villages, crops and orchards are often on sunny slopes.
PYQ Practice — Statement Analysis
1 Latitude is the most important factor affecting temperature.
It decides the angle of the Sun's rays.
2 Coastal areas have a larger annual temperature range than inland areas.
Coastal areas have a smaller range.
3 Temperature normally falls with altitude in the troposphere.
About 6.5 degrees Celsius per km.
4 Cold ocean currents raise the temperature of the coast.
They lower it.
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